Flame-retardant nylon fiber and method for producing the same

Abstract

This invention provides a flame-retardant nylon fiber and its preparation method. The flame-retardant nylon fiber is composed of nylon resin and 3-8 wt% of guanidine monochlorotriazine phosphite triethyl ester modifier. The modifier is chemically bonded to the nylon resin molecular chain. During synthesis, the dried nylon resin and the modifier are melt-blended at 250-280°C under nitrogen protection, and the finished product is obtained by extrusion, stretching, and heat setting. This invention, through a phosphorus-nitrogen synergistic flame-retardant mechanism, endows the nylon fiber with long-lasting and highly efficient flame-retardant properties without affecting its original strength, hand feel, breathability, moisture permeability, and skin-friendliness. The flame-retardant components are not easily lost, and the process is environmentally friendly and non-toxic. It is suitable for fire-fighting clothing, protective clothing, military textiles, home decoration fabrics, and other applications, solving the problems of difficulty in balancing flame-retardant efficiency and fiber performance, poor durability, and insufficient environmental protection in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of textile materials technology, specifically to a flame-retardant nylon fiber and its preparation method. Background Technology

[0002] With the increasing awareness of social safety, the demand for flame-retardant textiles in industrial protection, military equipment, and civilian household applications is growing. Nylon fiber, as a commonly used textile material, has excellent mechanical strength, abrasion resistance, and elasticity, and is widely used in the textile industry. However, nylon fiber itself is flammable, has a low limiting oxygen index, and produces molten dripping during combustion, which can easily cause secondary injuries. This greatly limits its application in high-risk environments and scenarios with high flame-retardant requirements.

[0003] To address the flame retardancy issue of nylon fibers, existing technologies mainly employ the following solutions: First, adding halogenated flame retardants, such as decabromodiphenyl ether, which offers good flame retardancy but releases toxic and harmful gases during combustion, posing a threat to the environment and human health, and is inconsistent with environmental protection trends. Second, using phosphorus-based flame retardants, such as red phosphorus and phosphate esters, which are relatively more environmentally friendly, but have limited flame retardancy efficiency, requiring large amounts to achieve the desired effect. However, high addition amounts significantly reduce the mechanical strength, elasticity, and abrasion resistance of nylon fibers. Third, using a nitrogen-phosphorus synergistic flame retardant system, such as a combination of ammonium polyphosphate and melamine, which improves the flame retardancy effect to some extent, but still suffers from insufficient flame retardancy efficiency and difficulty in meeting high-standard flame retardancy requirements. Fourth, applying a flame-retardant coating to the surface, which is simple and low-cost, but the coating has weak adhesion to the fiber matrix, easily peels off after repeated washing, has poor flame retardancy durability, and affects the fiber's breathability and comfort.

[0004] Therefore, developing a technical solution that can endow nylon fibers with long-lasting and efficient flame retardant properties without affecting their original excellent properties, and that is environmentally friendly and does not release toxic or harmful substances, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a flame-retardant nylon fiber and its preparation method, which solves the problems of low flame-retardant efficiency, poor durability, and impact on the original mechanical properties and comfort of nylon fibers after flame-retardant treatment in the prior art, as well as the environmental toxicity of some flame retardants. The invention achieves the endowment of nylon fibers with long-lasting and highly efficient inherent flame-retardant properties while maintaining the original strength, feel, breathability, moisture permeability and skin-friendliness of nylon fibers.

[0006] This invention is implemented as follows: A flame-retardant nylon fiber is composed of nylon resin and a modifier, wherein the modifier is guanidine monochlorotriazine triethyl phosphite, and the amount added is 3-8% of the weight of the nylon resin.

[0007] Furthermore, the amount of the modifier guanidine monochlorotriazine triethyl phosphite is preferably 5% of the weight of the nylon resin.

[0008] Furthermore, the nylon resin is PA6 or PA66.

[0009] Furthermore, the method for preparing the flame-retardant nylon fiber includes the following steps: S1: Add dried nylon resin chips to the reactor; S2: Add a measured amount of guanidine monochlorotriazine triethyl phosphite modifier to the reaction vessel; S3: Under nitrogen protection, raise the temperature inside the reactor to 250-280℃ to carry out a melt blending reaction; S4: After the reaction is complete, the melt is extruded through a spinneret to form a shape; S5: Flame-retardant nylon fiber is obtained by stretching and heat setting of the extruded fiber.

[0010] Furthermore, the drying conditions for the nylon resin chips in step S1 are: temperature 80-100℃, drying time 4-6 hours, and moisture content of the dried chips ≤0.05%.

[0011] Furthermore, the melt blending reaction in step S3 takes 1-3 hours, and the stirring rate during the reaction is 50-100 r / min.

[0012] Furthermore, in step S5, the stretching ratio is 3-5 times, the heat setting temperature is 120-150℃, and the heat setting time is 30-60 seconds.

[0013] Furthermore, the flame-retardant nylon fiber is used in the production of fire-fighting suits, protective clothing, military textiles, or home decor fabrics.

[0014] The present invention has the following advantages: Excellent and durable flame retardant performance: This invention introduces phosphorus-nitrogen synergistic flame retardant components into the molecular chain of nylon resin through chemical bonding, giving nylon fiber inherent flame retardant properties. According to the test, the limiting oxygen index of the flame retardant nylon fiber is ≥30%, the vertical burning performance reaches the B1 level standard in GB / T 5455-2014, and after 50 standard washes, the flame retardant performance does not decrease significantly. The flame retardant durability is significantly better than the existing surface coating or physical mixing flame retardant technical solutions. Maintaining the original excellent properties of the fiber: The modifier added in this invention is only 3-8%, and it is combined with the fiber matrix through chemical bonding. It will not damage the molecular structure and aggregate structure of the nylon resin. The resulting flame-retardant nylon fiber has a breaking strength ≥5.0cN / dtex and a breaking elongation of 25-40%, maintaining the original excellent strength, elasticity and abrasion resistance of the nylon fiber. At the same time, the breathability, moisture permeability and skin-friendliness of the fiber are not affected, making it comfortable to wear. The process is environmentally friendly and safe: the modifier of this invention itself does not contain any toxic or harmful substances, and no polluting substances such as halogenated flame retardants are used in the synthesis process. Moreover, no toxic gases are released during the reaction process, which meets the requirements of green chemistry. At the same time, the flame retardant components are firmly bonded to the fiber matrix, and the use process will not cause environmental pollution due to the migration or shedding of flame retardants. The processing technology is simple and feasible: The preparation method of the present invention is based on the existing melt spinning process of nylon fiber. It only requires adding modifiers to the raw materials and adjusting the relevant process parameters. It does not require major modifications to the existing production equipment, making it easy to achieve industrial production and controllable production costs. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of the combustion of the flame-retardant nylon fiber of the present invention. Detailed Implementation

[0017] The present invention relates to a flame-retardant nylon fiber, which is composed of nylon resin and a modifier, wherein the modifier is guanidine monochlorotriazine triethyl phosphite, and the amount of the modifier added is 3-8% of the weight of the nylon resin, preferably 5%.

[0018] The nylon resin is selected from PA6 or PA66, which has excellent mechanical and processing properties, providing a guarantee for the basic properties of the fiber; the modifier guanidine monochlorotriazine triethyl phosphite contains two flame retardant elements, phosphorus and nitrogen, and has active groups in its molecular structure, which can chemically bond with the nylon resin molecular chain to achieve a firm bond between the flame retardant component and the fiber matrix.

[0019] This invention also relates to a method for synthesizing flame-retardant nylon fibers, comprising the following specific steps: S1: Pretreatment of nylon resin chips: Place PA6 or PA66 nylon resin chips in a drying device and dry them at 80-100℃ for 4-6 hours to ensure that the moisture content of the chips is ≤0.05% in order to avoid the formation of bubbles and defects in the fibers due to the presence of moisture during subsequent melt processing, which would affect the fiber performance. S2: Raw material mixing: Add the dried nylon resin slices into the reactor, and then add the metered monochlorotriazine triethyl phosphite guanidine modifier according to the set ratio (3-8% of the weight of nylon resin); S3: Melt blending reaction: Nitrogen gas is introduced into the reactor for protection to prevent the raw materials from oxidizing and degrading at high temperature. Then, the temperature inside the reactor is raised to 250-280℃, and the stirring device is started. Stirring is carried out at a rate of 50-100r / min to fully melt and blend the nylon resin and the modifier and react. The reaction time is 1-3 hours. During this reaction, the active groups in the guanidine monochlorotriazine triethyl phosphite molecule undergo a chemical bonding reaction with the terminal amino groups on the nylon resin molecular chain, stably introducing phosphorus and nitrogen flame retardant elements into the polymer molecular chain to form modified nylon resin. S4: Extrusion molding: After the reaction is complete, the molten modified nylon resin is extruded through a spinneret to form nascent fibers; S5: Post-treatment: The nascent fibers are stretched by 3-5 times to improve the orientation and crystallinity of the fibers and enhance their mechanical strength; then, they are heat-set at 120-150℃ for 30-60 seconds to eliminate internal stress and improve the dimensional stability and elasticity of the fibers, ultimately producing flame-retardant nylon fibers.

[0020] The flame-retardant nylon fiber of this invention exhibits excellent flame-retardant properties based on a phosphorus-nitrogen synergistic flame-retardant mechanism: During fiber combustion, phosphorus promotes fiber dehydration and char formation, creating a dense, heat-insulating char layer. This char layer blocks heat transfer and oxygen contact, inhibiting further fiber combustion. Nitrogen releases non-flammable gases during combustion, diluting the oxygen concentration in the combustion zone. It also has a synergistic effect on the char formation process of phosphorus, further enhancing the flame-retardant effect.

[0021] Because the flame-retardant components are firmly bonded to the nylon resin molecular chains through chemical bonding rather than physical mixing or surface adhesion, the flame-retardant components are not easily lost. Even after multiple washes, they can still maintain excellent flame-retardant properties, achieving intrinsic flame retardancy.

[0022] The following will be combined with the appendix Figure 1 The technical solution of the present invention will be clearly and completely described in detail with specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products. Example 1

[0023] Raw material preparation: PA6 nylon resin chips are selected, and guanidine monochlorotriazine phosphite triethyl ester modifier is added at 3% of the weight of PA6 nylon resin; Pretreatment: PA6 nylon resin chips were dried at 80℃ for 6 hours, and the moisture content of the chips was controlled to be 0.04%. Mixing and reaction: Add the dried PA6 nylon resin chips to the reactor, then add the measured amount of modifier, purge with nitrogen for protection, heat to 250℃, and stir at 50r / min for 3 hours. Extrusion molding: Molten modified PA6 resin is extruded through a spinneret to form nascent fibers; Post-processing: The nascent fibers are stretched at 3 times the stretch ratio and then heat-set at 120°C for 60 seconds to obtain flame-retardant nylon fibers. Example 2

[0024] Raw material preparation: PA66 nylon resin chips are selected, and guanidine monochlorotriazine phosphite triethyl ester modifier is added at 5% of the weight of PA66 nylon resin; Pretreatment: PA66 nylon resin chips were dried at 90℃ for 5 hours, and the moisture content of the chips was controlled to be 0.03%. Mixing and reaction: Add the dried PA66 nylon resin chips to the reactor, then add the measured amount of modifier, purge with nitrogen for protection, heat to 265℃, and stir at 80r / min for 2 hours. Extrusion molding: Molten modified PA66 resin is extruded through a spinneret to form nascent fibers; Post-processing: The nascent fibers are stretched at a stretch ratio of 4, and then heat-set at 135°C for 45 seconds to obtain flame-retardant nylon fibers. Example 3

[0025] Raw material preparation: PA6 nylon resin chips are selected, and guanidine monochlorotriazine phosphite triethyl ester modifier is added at 8% of the weight of PA6 nylon resin; Pretreatment: PA6 nylon resin chips were dried at 100℃ for 4 hours, and the moisture content of the chips was controlled to be 0.02%. Mixing and reaction: Add the dried PA6 nylon resin chips to the reactor, then add the measured amount of modifier, purge with nitrogen for protection, heat to 280℃, and stir at 100r / min for 1 hour. Extrusion molding: Molten modified PA6 resin is extruded through a spinneret to form nascent fibers; Post-processing: The nascent fibers are stretched by 5 times the stretch ratio and then heat-set at 150°C for 30 seconds to obtain flame-retardant nylon fibers.

[0026] Performance testing like Figure 1 As shown in the figure, a burning test was conducted on the fabric woven from the product of Example 3. The results show that: 0 seconds: The sample is light-colored and unignited; 1-7 seconds: After the flame source comes into contact with the sample, the contact area gradually turns black, and the burning range slowly expands, but there is no flame spread; 8-9 seconds: After the flame source is removed, the sample continues to smoke and stops burning. It can be seen that the flame-retardant nylon fiber of the present invention has excellent flame-retardant effect.

[0027] The flame-retardant nylon fibers obtained in Examples 1-3 above were subjected to performance tests, while conventional PA6 and PA66 nylon fibers that had not undergone flame-retardant treatment were used as a control group. The test results are shown in the table below:

[0028] The test results show that the flame-retardant nylon fiber produced by this invention has a limiting oxygen index of ≥30% and a vertical burning performance of B1 level, demonstrating excellent flame-retardant properties. At the same time, its breaking strength, breaking elongation, air permeability, and other performance indicators are close to those of conventional nylon fiber, maintaining the original excellent mechanical properties and comfort of nylon fiber. After 50 washes, the flame-retardant performance does not decrease significantly, and the flame-retardant durability is good, fully meeting the usage requirements of fire suits, protective clothing, military textiles, home decoration fabrics, and other scenarios.

[0029] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A flame-retardant nylon fiber, characterized in that: It is composed of nylon resin and a modifier, wherein the modifier is guanidine monochlorotriazine triethyl phosphite, and the amount added is 3-8% of the weight of the nylon resin.

2. The flame-retardant nylon fiber according to claim 1, characterized in that: The preferred amount of the modifier, guanidine monochlorotriazine triethyl phosphite, is 5% of the weight of the nylon resin.

3. The flame-retardant nylon fiber according to claim 1, characterized in that: The nylon resin is PA6 or PA66.

4. A method for preparing flame-retardant nylon fiber as described in any one of claims 1-3, characterized in that: Includes the following steps: S1: Add dried nylon resin chips to the reactor; S2: Add a measured amount of guanidine monochlorotriazine triethyl phosphite modifier to the reaction vessel; S3: Under nitrogen protection, raise the temperature inside the reactor to 250-280℃ to carry out a melt blending reaction; S4: After the reaction is complete, the melt is extruded through a spinneret to form a shape; S5: Flame-retardant nylon fiber is obtained by stretching and heat setting of the extruded fiber.

5. The preparation method according to claim 4, characterized in that: The drying conditions for the nylon resin chips in step S1 are: temperature 80-100℃, drying time 4-6 hours, and moisture content of the dried chips ≤0.05%.

6. The preparation method according to claim 4, characterized in that: The melt blending reaction in step S3 takes 1-3 hours, and the stirring rate during the reaction is 50-100 r / min.

7. The preparation method according to claim 4, characterized in that: The stretching ratio in step S5 is 3-5 times, the heat setting temperature is 120-150℃, and the heat setting time is 30-60 seconds.

8. The application of flame-retardant nylon fiber according to any one of claims 1-3 in the production of fire-fighting suits, protective suits, military textiles or home decoration fabrics.

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